This invention to a deck plank for use on a boat dock, a residential deck, a hog farrowing house floor, or the like where the deck plank is extruded from a suitable synthetic resin, such as polyvinyl chloride (PVC) or the like, such that the deck plank is light in weight and is resisitive to weathering without the need of painting or other maintenance upkeep. In this disclosure, it will be understood that the deck plank of this invention may have many uses, but, for the sake of simplicity, the primary application disclosed herein will be in the context of a deck plank for a boat dock.
Typically, a boat dock has a number of pilings sunk in the bottom on the body of water with joists or other horizontal support members secured to the pilings. In the case of a floating dock, a horizontal frame is supported by floatation members mounted within the frame. These dock joists or frames have deck planks secured to the horizontal support members for forming a deck on which persons may walk. In the past, the conventional dock construction technique was to use wooden joists and frame members of 2.times.6, 2.times.8, or 2.times.10 lumber, or the like. The deck planks were conventionally 2.times.6 or 2.times.8 lumber fastened to the top surfaces of the joists with a slight gap (e.g., 1/4 to 1/2 inch) between adjacent deck planks to permit water to readily drain from the deck. However, wooden deck planks, even when pressure treated lumber is used, tend to deteriorate over time, especially when exposed to the constantly wet environment of a boat dock and when the dock is on a body of salt water. In addition, pressure treated lumber is difficult to paint and some persons object to the natural "greenish" color of most pressure treated lumber. There is also a concern that the preservative used to treat pressure treated lumber may leach out of the lumber and contaminate the water surrounding a dock made of such pressure treated lumber.
Deck planks of materials other than wood, including polyvinyl chloride, have been used, but all of these prior alternative deck plank materials have had their shortcomings. In U.S. Pat. No. 4,078,515 to Svirklys, deck planks of extruded aluminum are disclosed which snap lock on to clips provided on the dock frame. However, such aluminum deck planks are expensive.
Misener, U.S. Pat. No. 4,349,297 describes a boat dock in which plastic resin planks are slideably engaged over tubular metal stringers.
U.S. Pat. No. 5,048,448 to Yoder discloses a boat dock structure including an elongate plank of extruded PVC plastic or the like. The plank has an upper surface which constitutes the walking surface of the plank, with flanges extending down from the sides and center of the plank so as to stiffen the plank. These flanges are the approximate thickness of a similar dimensioned wood lumber plank. The plastic plank described in this prior art patent is secured to the dock joists or support members by means of plastic clips with one clip secured to the upper surface of each of the dock support joists or frame members. Then the planks are snapped into the clips so as to secure the planks to the support members.